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by "compile mode," I presume you mean "Memory Model?" Yes, of course you can! The Memory Model simply defines the default memory space (see the Manuals) - you can always explicitly use the memory-space qualifiers to choose a specific memory space. You have read the uVision Getting Started Guide, and worked through the example projects in it, haven't you...? This will give you a proper introduction to the tools, rather than just jumping blindly into the deep end.